Changing chemistry in the world's oceans could affect the ability of a snail to defend itself.

By Emily Sohn, 00:00 AM October 19, 2007

Conditions in the world's oceans are changing, thanks to human activities. And those changes might be affecting the ability of a small snail to defend itself, suggests a new study.

Factories, cars, and other machines spit out lots of a gas called carbon dioxide. Carbon dioxide (CO2) is known as a greenhouse gas because it traps heat in the atmosphere. More and more of the gas has been accumulating in the air in recent years.